JP2009097514A - Cylinder having means for receiving lubricant - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means of uniformly distributing a lubricant throughout the length of a cylinder and reducing the consumption of the lubricant. <P>SOLUTION: The cylinder 1 for an piston engine includes a means 5 for receiving the lubricant. The cylinder has a sliding surface 7 for a piston 2, which is the sliding surface 7 having a top dead zone 8 and a row of scavenging slots 6 arranged on the cylinder. The sliding surface 7 has a plurality of slot-shaped pits 5 having a predetermined length 9, a width 10, and a depth 11 of over 0.4 mm. The slot-shaped pit 5 is provided in a position lower than the ring-shaped area 12 of the cylinder surface having a length of up to 15% of the length 13 of the sliding surface 7 which has been measured from the top dead zone 8. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cylinder for a piston engine including means for receiving a lubricant.

  In large two-stroke engines, or even in large four-stroke engines, lubricant distribution has been found to be important as a result of its wide surface that must be wetted. Lubricant passes through a limited number of feed openings located at the periphery of the cylinder towards the interior space of the cylinder. In order to evenly distribute the liquid lubricant over the entire inner wall of the cylinder, a groove is provided extending around the periphery, as shown, for example, in French patent application 1174532. However, in long-term engine operation, especially in parts of the cylinder that are subjected to high loads up to about 15% from the top dead center of the top piston ring to the bottom dead center of the piston, the grooves are subject to significant wear. Has been shown to receive. The high pressure that can reach up to 200 bar, which is dominant in this region, and the high temperature that can reach over 300 ° C., increase the cross section of the piston and the cross section of the piston ring due to thermal expansion. A loosely arranged piston ring is pushed by this pressure in the direction towards the inner wall of the cylinder. This is desirable for increasing the pressure in the combustion space, but it also involves severe loading of the inner wall of the cylinder due to shear forces. In long-term operation, these shear forces cause wear or flattening of the profile formed by the groove extending to the periphery. This inevitably results in long-term operation no longer guaranteeing a uniform distribution of lubricant. If there is no uniform distribution of the lubricant, at least locally hard material friction, i.e. direct contact between the outer surface of the piston ring and the cylinder wall, thereby not only impairing the sliding properties, There is also a possibility that the inner wall of the aforementioned cylinder may be worn or even damaged. In order to solve this problem, WO 98/53192 pamphlet is provided with a ring-shaped groove or a groove designed as a groove portion arranged on the periphery of the cylinder in a portion that receives a high load of the cylinder. Has been advocated. Thus, it is actually possible to distribute the lubricant more evenly in the high load area of the cylinder wall. However, this improvement is limited to a length region of up to 15% starting from the top dead center of the top piston ring described above. Furthermore, the ring-shaped groove has other disadvantages. The edges of the piston ring are engaged with the edges of the groove, so that these edges are subject to strong wear, which can cause edge damage.

  For all these reasons, the actual lubricant consumption is greater than the amount of lubricant required to lubricate the sliding pair of pistons and cylinders. In large diesel engines, the cost is substantial, but in addition, the consumption of lubricants is also an environmental burden. Many portions of the exhaust gas particles that are released are generated from the lubricant.

  Accordingly, an object of the present invention is to evenly distribute the lubricant over the entire length of the cylinder from at least the top dead center of the uppermost piston ring to the bottom dead center, while simultaneously reducing the amount of lubricant consumed. That is. In this regard, there is no need to change the number and position of the feed openings. In particular, the role of the lubricant for the two-stroke engine is not only to ensure proper piston lubrication, but also to neutralize the sulfuric acid entering the combustion space by the combustion of fuel containing sulfur.

  The problem is a cylinder for a piston engine that includes means for receiving a lubricant, including a sliding surface for the piston, the sliding surface being a top dead zone and a row of scavenging slots disposed within the cylinder. Is solved by a cylinder having The top dead zone is defined as the plane on which the top dead center of the piston ring is located. The sliding surface has a plurality of slot-shaped recesses. The slot-like recess has a predetermined length, width and depth reaching more than 0.4 mm. The slot-like recess is provided below the ring-shaped area of the cylinder surface having a length of up to 15% of the length of the sliding surface measured from the top dead area. Surprisingly, the area of the cylinder that receives the highest load need not be slotted, but rather outside of the highest load area, ie 15% of the sliding surface below the top dead area referred to above. It has been shown that it is advantageous to arrange a plurality of slot-like recesses. The piston ring draws the lubricant and carries it in the process of reaching the highest load area. In order to evenly distribute the lubricant, it may actually be advantageous to have no slot-like recesses in this highest load area.

  According to an advantageous embodiment, slotted recesses are also provided in and below the area of the flushing slot.

  The width of the slot recess is between 0.5 and 3 mm, but in any case it should be less than 80%, preferably 70% and particularly preferably less than 60% of the width of the narrowest piston ring. . This ensures that the piston ring slides without tilting and without contact over the recess.

  The length of the slot-shaped recess is between 10 and 100 mm, preferably between 10 and 50 mm, particularly preferably between 10 and 30 mm.

  It is possible to arrange a plurality of slot-like recesses in a row. The number of slot-like recesses in the row is preferably 10 to 150, depending on the length of the slot-like recesses and the distance between two adjacent slot-like recesses. The length and spacing of the slot-like recesses are preferably selected such that the notch effect caused by the slot-like recesses is lower than the allowed cylinder weakening. According to certain advantageous embodiments, the length of the spacing is greater than the length of the slot-like recess.

  The rows have a slope or slope, which is preferably less than the slope corresponding to the height of the piston ring. Therefore, the maximum angle of the gradient of the slot-like recesses in the row is 1 °. This dimension also helps to increase the smoothness of the piston ring during travel. That is, contact between the edge of the slot-like recess and the piston ring always occurs at only one point. As a result, the angle of the gradient prevents the surface contact of the edge of the piston ring against the edge of the slotted recess, thereby preventing the application of shear forces to the edge of the slotted recess. There is almost no wear of the material. Therefore, the operating life of the cylinder can be increased by maintaining the gradient.

  For example, if the cylinder diameter is 190 mm, the piston ring has a width of 5-10 mm, in which case the maximum angle of the gradient is 0.96 °.

  If the cylinder diameter is 400 mm and the piston ring width is 10-15 mm, the maximum angle of the gradient is 0.68 °.

  The number and / or depth and / or length and / or width of the slot-like recesses may be different from each other. Advantageously, the slot-like dimensions of adjacent rows are configured to be offset from each other. The offset allows the inner wall of the cylinder wall to be ideally wetted with lubricant while minimizing the weakness of the cylinder jacket.

The number of slot-shaped recesses is 300 or more per 1 m ² of the sliding surface. Since each part of the sliding surface must withstand a different load, the number of slot-shaped recesses per 1 m ^{2 of} the sliding surface is not constant.

  The method for manufacturing the means for receiving the lubricant in the cylinder according to the previous embodiment comprises the step of manufacturing the slot-like recess by a mechanical processing method.

  Cylinders are used in large diesel engines, such as 2-stroke engines or 4-stroke engines.

  Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

  FIG. 1 shows a cross-sectional view through a cylinder 1 arranged in a piston engine. The piston engine is a two-stroke engine or a four-stroke engine, particularly a large diesel engine. Such large diesel engines typically include cylinders that are generally greater than 190 mm in inner diameter. A typical diameter is between 250 and 1000 mm. The piston reciprocates inside the cylinder and is connected to a rotatable drive shaft via a connecting rod. The reciprocating motion of the piston is performed between the top dead center and the bottom dead center. FIG. 1 shows the piston at the position of top dead center. Considering a cutting plane that passes through the top dead center of the top piston ring and is perpendicular to the axis of the cylinder, that plane intersects the inner wall of the cylinder along a line referred to below as top dead zone 8. When the cylinders are arranged vertically, the top dead area 8 forms the uppermost boundary of the sliding surface 7. Considering a similar cut through the bottom dead center of the bottom piston ring, the bottom dead zone 15 is obtained in the same way. The length L (13) indicates the distance between the upper dead area 8 and the lower dead area 15, and corresponds to the length of the sliding surface. The sliding surface can have a length of 1 m to about 4 m. The width of the sliding surface is formed by the peripheral edge of the upper dead area 8 and the peripheral edge of the lower dead area 15. Since the internal space of the cylinder is generally not cylindrical but slightly conical, the width of the sliding surface in the top dead zone 8 is greater than the width of the sliding surface in the bottom dead zone 15. This conical shape is due to the various temperatures appearing in different areas of the sliding surface. In the area of the bottom dead zone, air is drawn from the environment, so that in this area the operating temperature is not so different from the ambient temperature of the air in the engine space. However, in the region of the top dead zone, temperatures above 300 ° C. may become dominant. Due to these considerable temperature differences, thermal expansion can occur, in particular leading to expansion of the piston ring 3 provided on the piston 2, and in the region of the bottom dead zone, the piston ring 3 is unacceptable. As a result, it is pressed against the inner wall of the cylinder, and as a result, it prevents formation of a thin film of lubricant. By introducing a lubricant covering the inner wall of the cylinder in the region of the sliding surface 7 as a thin film of lubricant as well as the measures to be taken against the friction of the undesired hard material between the inner wall of the cylinder and the piston ring. is there. The lubricant is fed into the space of the cylinder through the lubricant supply path 4. A plurality of feed openings 16 can be provided dispersed on the peripheral edge of the cylinder. A flow path 17 starts from the feed opening and extends along the inner wall of the cylinder and is used to transport and distribute the lubricant. When the cylinder is oriented vertically, the lubricant wets the entire sliding surface below the flow path. When the piston 2 moves in the expansion phase and passes through the feed opening, the lubricant is carried by the piston ring 3 sliding on the inner wall of the cylinder, and there is no longer any lubricant available for the next lubrication. Disappear. This increases the amount of lubricant consumed and, if the surface to be wetted with such a lubricant is large, it becomes a cost factor that cannot be ignored.

  The cylinder 1 includes means 5 for receiving a lubricant arranged on the sliding surface 7 for the piston 2. The sliding surface extends between the upper dead area 8 and the lower dead area 15. When arranged vertically, the bottom dead zone 15 is located below the row of scavenging slots 6 arranged on the cylinder. A plurality of slot-shaped recesses 5 are arranged on the sliding surface 7. The slot recess acts as a lubricant pocket. When lubricant is supplied through the feed opening 16, the lubricant flows downward along the cylinder wall and into the slot-like recess that forms a storage area for the lubricant. The slot-like recesses located above the feed opening are filled with lubricant as the piston ring slides past the slot-like recesses. The piston ring carries lubricant during its movement, and as the piston ring passes through such slot-like recesses, the lubricant is deflected and enters the slot-like recesses, filling the slot-like recesses. The slot-like recess has a length l (9), a width b (10), and a depth t (11), which are shown in detail in FIG. The depth 11 reaches more than 0.4 mm, which guarantees that the slot-like recess remains intact for several years of operation, even if the inner cylinder wall is worn. The greater depth of the slot recess has the further advantage that the lubricant pushed by the piston ring flows over the inner wall of the cylinder throughout the next stroke and wets the inner wall with a thin film of lubricant. Arranging the plurality of slot-like recesses ensures that the entire sliding surface or at least a part thereof having such slot-like recesses is wetted. The slot-shaped recess 5 is in particular provided below the ring-shaped region (12) of the cylinder surface, which has a length of up to 15% of the length L (13) of the sliding surface 7 measured from the top dead zone 8. . This arrangement not only significantly reduces lubricant consumption but also increases the operating life of the cylinder surface. The main reason for the reduced consumption of the lubricant is that the lubricant is stored in the slot-shaped recess. Thus, the lubricant does not flow away after the operating cycle, i.e. it is not expelled by the piston ring and remains largely in the slot recess. As a result, the lubricant can be utilized for the next operating cycle. The operating life of the cylinder surface is increased because the highest load area is not provided with slotted recesses, or is provided only with a significantly reduced number of slotted recesses, so that the maximum load area on the inner wall of the cylinder is reduced. This is because it is not weakened by a plurality of small notches or slot-like recesses or by a groove extending to the perimeter known in the prior art.

  Cylinder operation even in slotted recesses with a depth of more than 0.4 mm, the wear was very severe in the area up to 15% of the sliding surface measured from the top dead area, that is, the highest load area, which was excluded earlier. Since it disappears before reaching the end of its lifetime, the use of slot-like recesses is limited. Especially for the reasons mentioned above, it can be advantageous to omit the slot-like recesses, especially in this highest load area, in order not to weaken the inner wall of the cylinder. Surprisingly, however, it may be further advantageous to provide a recess in the area outside this area so that the lubricant utilized therein is carried by one of the plurality of piston rings to the highest load area. Indicated. In particular, the area 1 in which the slot-shaped recess is provided is up to 25%, preferably 10-25%, particularly preferably 15% -20%. In FIG. 1, the highest load area, i.e. the ring-shaped region 12, is shown not to include a slot-like recess. Three rows of slot-like recesses are shown below the piston, but for the sake of clarity, a more detailed representation of the other rows up to the lubricant supply path 4 is omitted. In order to ensure a proper supply of lubricant, it is advantageous to provide a slot-like recess in the entire surface 7 except for the highest load area. In particular, slot-like recesses can also be provided in the region of the scavenging slot 6 and below it. Even in this region, damage due to wear has been found in the past. Again, this wear was due to inadequate and inadequate lubricant supply. For the sake of convenience, the lubricant introduced by the lubricant supply path 4 is periodically supplied at the position of the piston shown in FIG. 1, because it is not necessary to supply the lubricant under pressure at this position. It is. Lubricant flows down along the inner wall of the cylinder and is then moved by the piston ring 3 of the piston in the expansion phase. Part of the lubricant will certainly reach the scavenging slot 6, but the lubricant can be stored there in the region of the scavenging slot when the piston is at the bottom dead center when the piston is at bottom dead center. Only if a slot-like recess is also provided up to the lowest position of the ring. In the absence of such slot-like recesses, the piston ring releases the remaining amount of lubricant that is no longer available for further lubrication. Furthermore, when the piston starts the compression stroke, there is the disadvantage that there is no more lubricant in the area of the scavenging slot. Therefore, at the start of the compression stroke, the piston ring 3 begins to dry. On the other hand, the lubricant stored in the slot-like recesses can be distributed over the entire inner wall of the cylinder in the area of the scavenging slot, thus ensuring proper lubrication for the compression stroke.

  FIG. 2a shows an exploded view of the cylinder in another possible slot-like recess arrangement, and FIG. 2b shows such a slot-like recess 5 in an enlarged form. The slot-like recess is defined by a length l (9), a width b (10) and a depth t (11). In an advantageous embodiment, the width of the slot-shaped recess is between 0.5 and 3 mm. The width b must be large enough to allow an appropriate amount of lubricant to be stored in the recess. On the other hand, the width b of the piston ring is such that the piston ring is not engulfed by the edge of the slot recess and that gas from the compression space does not reach the suction space through the slot recess. Must be smaller than the width. When a gas leakage flow occurs through such a recess, the pressure increase in the compression space changes and the efficiency of the engine decreases accordingly. The length of the slot-shaped recess is between 10 and 100 mm, preferably between 10 and 50 mm, particularly preferably between 10 and 30 mm. It is advantageous to arrange a plurality of slot-like recesses in a row, which can have a slope. The slope is limited to dimensions smaller than the piston ring width for the reasons listed in connection with the recess width. The angle 18 of the slope of the slot-shaped recess is 1 ° at the maximum. The number of slot-like recesses in a row may be different from the number of slot-like recesses in an adjacent row. The number and / or depth t (11) and / or length l (9) and / or width b (10) of the slot-like recesses may be different from each other.

In all of FIGS. 1-3, the slot-like recesses of adjacent rows are arranged at least partially offset with respect to each other. In this way, it is possible to increase the number of slot-shaped recesses per 1 m ^{2 of} the sliding surface, ensuring the most even distribution of lubricant that can be implemented. The number of slot-shaped recesses is preferably 300 or more per 1 m ² of the sliding surface. When it is possible to find areas of the sliding surface where the required amount of lubricant increases or decreases during operation, the number of slot-shaped recesses per 1 m ² of the sliding surface can be variably selected. As can be seen in FIG. 2, it is possible, for example, to reduce the number of slot-like recesses or to increase the spacing between adjacent rows of slot-like recesses.

  FIG. 3 shows a view of the sliding pair of piston rings and the inner wall of the cylinder for the previous embodiment. In this case, no slot-like recess is provided in the ring-shaped region 12 which is a maximum of 15% of the sliding surface and which is disposed immediately below the top dead zone 8. The piston 2 is at a lower position than the ring-shaped region 12. It can be particularly advantageous if the region 12 is increased to 25% of the sliding surface. Particularly in that case, the region 12 is 10 to 30%, preferably 15 to 30%, and the region is particularly preferably more than 25% and 30% or less.

  The slot-shaped recess is manufactured by a mechanical machining process. This includes, for example, a chip-forming process such as milling, but does not include a method of processing under the influence of heat, such as structuring using a laser. The laser structuring method is used in particular for the production of grooves in the micrometer range and is not suitable for the production of slot-like recesses with a depth in the millimeter range.

  Cylinders that are already in use can be retrospectively provided with slot-like recesses in regular inspection work and repair. Particularly in a cylinder used in a large diesel engine, the required amount of lubricant can be reduced by providing the slot-like recesses retrospectively in a planned manner.

It is sectional drawing which passes along a cylinder. It is an expanded view of a cylinder. It is a figure which shows a slot-shaped arrangement | positioning in detail. FIG. 5 is a view of a sliding piston ring and inner wall of a cylinder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Piston 3 Piston ring 4 Lubricant supply path 5 Slot-shaped recessed part 6 Scavenging slot 7 Sliding surface 8 Top dead area 9 Slot-shaped recessed part length 10 Slot-shaped recessed part width 11 Slot-shaped recessed part Depth of 12 Ring-shaped region 13 Length of sliding surface 15 Bottom dead zone 16 Feed opening 17 Flow path 18 Angle of gradient of slot-shaped recess

Claims (14)

A cylinder (1) for a piston engine comprising means (5) for receiving a lubricant, the cylinder comprising a sliding surface (7) for the piston (2), said sliding surface being a top dead zone (8) and a row of scavenging slots (6) arranged on the cylinder, and the sliding surface (7) has a predetermined length (9), width (10) and depth ( In a cylinder (1) for a piston engine having a plurality of slot-like recesses (5) having 11), the depth (11) being greater than 0.4 mm,
From the ring-shaped area of the cylinder surface, the slot-shaped recess (5) has a length up to 15% of the length (13) of the sliding surface (7) as measured from the top dead area (8). A cylinder characterized by being provided below.   The cylinder according to claim 1, wherein the slot-like recess is also provided in and below the region of the scavenging slot.   The cylinder according to claim 1, wherein the width (10) of the slot-like recess is between 0.5 and 3 mm.   Cylinder according to claim 1, wherein the length (9) of the slot-like recess is between 10 and 100 mm, preferably between 10 and 50 mm, particularly preferably between 10 and 30 mm.   The cylinder according to claim 1, wherein a plurality of slot-like recesses are arranged in a row.   The cylinder according to claim 5, wherein the row is inclined.   The cylinder according to claim 6, wherein the inclination angle of the slot-like recess is 1 ° at the maximum.   The cylinder according to any one of claims 5 to 7, wherein the slot-like recesses in adjacent rows are offset from each other.   The number of the slot-like recesses in different rows and / or the depth (11) and / or the length (9) and / or the width (10) of the slot-like recesses are different from one another. The cylinder according to any one of claims 1 to 8. The cylinder according to any one of claims 1 to 9, wherein the number of the slot-like recesses is 300 or more per 1 m ^{2 of the} sliding surface. The cylinder according to claim 8, wherein the number of the slot-like recesses per 1 m ^{2 of the} sliding surface is indefinite.   The cylinder according to any one of claims 1 to 11, wherein the cylinder has a diameter greater than 190 mm.   13. A method for producing means for receiving a lubricant in a cylinder according to any one of claims 1 to 12, wherein the slot-like recess is produced by a mechanical machining process. Method.   Use of a cylinder according to any one of claims 1 to 13 in a large diesel engine.

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